This invention relates to a controller for auxiliary braking devices on tractor trailers equipped with auxiliary braking devices, such as exhaust brakes and retarder brakes.
FIGS. 6A and 6B show examples of the tractor trailers.
FIG. 6A shows a full tractor trailer (1) which is comprised of a tractor (10) and a trailer (20). The tractor (10) has an engine with an exhaust brake (12), rear drive wheels (16), and a retarder (referred to as "tractor retarder") (14) placed between a transmission output axis and driving wheels (16). The trailer (20), which is connected to the tractor (10) via a coupler (22), has non powered, free rolling front wheels (23) and rear wheels (24), and a retarder (referred to as "trailer retarder") (26) arranged at a differential gear (25) that couples the left and right rear wheels (24).
FIG. 6B shows a semi-tractor trailer (1A) which is comprised of a tractor head (30) and a trailer (40). The tractor head (30) has an engine with an exhaust brake (12), rear drive wheels (34), and a tractor retarder (14) placed between a transmission output axis and the drive wheels (34). A trailer retarder (26) is connected to a differential gear (43) that couples left and right rear wheels (42) of the trailer (40).
This type of retarder is disclosed in Japanese Laid-Open Utility Model No. 5-54130 (1993).
This type of tractor trailer is equipped with control switches for the exhaust brake and retarders, operated by the driver.
Switching patterns for the braking devices, however, are diversified, and it is difficult to maintain optimum operating conditions at all times because, depending on the driving (braking) conditions, the exhaust brake, tractor brake and trailer retarder respectively have their own unique "braking properties" and "effects on interlocking properties of the vehicles when braking".
For instance, it is difficult to perform optimal switching while driving under the following conditions:
(1) The braking force of the exhaust brake is large when in low gears, and that force is only effective for the tractor. Thus, when used alone, the exhaust brake may cause the truck to so called "jackknife". Drivers should avoid using the exhaust brake or, if its use is unavoidable, the simultaneous use of a trailer retarder is required.
(2) When using the trailer retarder, the driver may desire to operate the trailer retarder alone if rear pulling is required on a downhill. On the other hand, the driver may need to simultaneously operate the tractor retarder and exhaust brake if a large braking force is desired.
(3) When all the retarders are used, it is not impossible to pull from the rear by using the trailer retarder alone, even when the driver desires to correct the attitude of the vehicle on a downhill.
This invention provides a controller for optimal control of the above-mentioned braking devices.